Leslie Morgan Steiner is an advocate and expert on violence against women. She is the author of The New York Times bestselling memoir, "Crazy Love." Her TEDTalk on why victims stay in abusive situations has been viewed by over 4 million people. She serves on the board of the One Love Foundation and DC Volunteer Lawyers Project. She lives in Washington, D.C. The views in this commentary are solely hers.

(CNN)Advocates who speak out against domestic violence debate the value of photos of bruises and strangulation marks on victims of intimate partner abuse. Why do victims need proof? Shouldn't victims' words be believed? But it's hard to look away from the photo of Rob Porter's former wife released to the media, and the yellow-purple bruise that blackens her eye.

Her husband, now a former White House staff secretary, allegedly did that to her, in a hotel room in Italy, 15 years ago, under the most romantic of circumstances. Would you want to be this man's girlfriend, wife, or daughter? Would you hire him, or vote for him? Would you want him working in the West Wing of the White House, controlling all information leading to the commander in chief?

Leslie Morgan Steiner

Of course, everyone's answer is no. And yet, despite two ex-wives with credible, consistent documentation that was shared with the FBI and at least some members of Trump's inner circle, Rob Porter was interviewed, hired and given elite political access into the top echelons of our government. Porter denied the allegations in a statement issued in the wake of his resignation.

Which explains why photographic evidence of abuse is necessary: it breaks through the powerful shield of denial. It's not an exclusive club, the ex-wives of abusive men. The National Domestic Violence Hotline estimates that one in three women are abused in their lifetimes. The challenge is how to break through the general public's ability to know about how common relationship violence is -- but still fail to take action about it.

Relationship abuse thrives when otherwise intelligent, powerful people ignore its warning signs. Visual proof is harder to ignore. In order to stop abusers, and to make powerful enablers like Chief of Staff John Kelly the exception, and not the norm, we all have to better understand how domestic violence unfolds, and the cost we all pay for it.

Read More

JUST WATCHED

Third woman contacted Porter's ex-wives

MUST WATCH

Third woman contacted Porter's ex-wives03:58

First comes the fairytale. Victims fall in love with the charming side of the abuser, a public persona. This potentially explains why John Kelly and White House senior aides who knew of the allegations -- not to mention Hope Hicks, who has been dating Porter -- all apparently worked willingly and peacefully with Rob Porter. White House press secretary Sarah Sanders defended Porter as "someone of the highest integrity and exemplary character." At work, perhaps Porter was.

But how a person treats his family members, the loved ones who are closest and most vulnerable to him, is the true test of character. The testimony and experiences of these intimates should never be ignored, especially because we know that men who abuse their wives and partners sometimes turn their rage outward: the Boston Marathon bomber, the Pulse nightclub shooter, and the Sutherland Springs shooter all had histories of relationship violence.

Abusers look like the rest of us, because they are the rest of us. Abuse happens in all religions, all countries, all neighborhoods -- at all income and education levels. Rob Porter graduated from Harvard one year ahead of Trump's son-on-law Jared Kushner. He's a Rhodes scholar. A lawyer. Exactly the type of person most people would consider "a good guy."

JUST WATCHED

Porter's ex-wife says he is abusive and angry

MUST WATCH

Porter's ex-wife says he is abusive and angry02:49

But abusive tendencies are triggered by the mix of isolation and intimacy that come with a sustained and intimate relationship. The next step of abuse is isolation, followed by the threat of violence, actual violence, profuse apology, and repeat. These are the sides of an abuser that only his (or her, because women are abusers, too) most loved ones see. The side ex-wives Colbie Holderness and Jennifer Willoughby tried to warn the Trump administration about. The side that Hope Hicks should be very, very worried about.

The lesson of the powerful #MeToo movement is that women's voices become amplified when we join together and corroborate each other's stories of violence and harassment. In essence, we become impossible to ignore.

The Daily Mail was able to break the Rob Porter story with confidence because his two ex-wives shared their stories honestly in FBI interviews that were part of their ex-husband's vetting for the staff secretary job in the Trump White House.

Despite Porter's resignation, the most troubling question remains: Why does it take so many women coming forward, and so much time passing, for people to believe us?

Victims need to speak out, to break the silence about relationship violence. But it's equally important that people in positions of power listen to us, and take action to ensure that there are no more victims.